Simulation study and field experiments on the optimal canopy shaking action for harvesting Camellia oleifera fruits

Abstract

With the increasing cultivation scale of Camellia oleifera in China, the demand on the mechanical harvesting machinery is very urgent. Inefficient fruit harvesting has become a bottleneck hindering the development of Camellia oleifera industry. In order to achieve high fruit harvesting percentage and low detachment percentage of the flower buds, a canopy shaking mechanism is proposed for massively harvesting Camellia oleifera fruits which applies the reciprocating linear motion of multiple beating-bar arrays to the tree canopy. The multiple beating-bar arrays driven by the eccentric disk can generate comb-brushing effects on the tree canopy. Three kinds of Camellia oleifera tree architecture were modelled and their dynamics were simulated by finite element analysis. Their modal analysis results show that the low-order natural frequencies of the Camellia oleifera trees with different canopy shapes are very close. According to harmonic response analysis, the low-frequency excitation is used to harvest Camellia oleifera fruit. The orthogonal experiments were carried out on the canopy shaker prototype with the motor speed, reciprocating stroke and duration of vibration as the influencing factors, and the fruit harvesting percentage and the detachment percentage of the flower buds as the evaluation indices. The results show that the same optimal parameter combination can be used for three kinds of Camellia oleifera tree architecture, in which the motor speed is 360 r/min, the reciprocating stroke is 80 mm and the duration of vibration is 8 s. The average fruit harvesting percentage is 72.3% and the average detachment percentage of the flower buds is 13.9%.

Simulation and experimental analysis of Camellia oleifera fruit shedding based on finite element explicit dynamics

“…Further research and development of C. oleifera fruit harvesting machinery can be expected. In the past, researchers have developed a variety of different mechanized harvesting equipment (Gao et al 2013;Gao et al 2019;Wu et al 2020;Du et al 2022a) for harvesting C. oleifera fruit, such as vibrating type, tooth comb type, and roller rubber type equipment (Du et al 2021;Du et al 2022b;Wu et al 2022c). However, because of the biological characteristics of C. oleifera fruit, there are some problems, such as insufficient separation force and misharvesting of flowering buds when using mechanized harvesting equipment (Chen et al 2019b).…”